# DF-2768 baseline (stock INVARIANTS kernel #0, default config)
# run as root:
$ /tmp/ptmx_limit_offbyone; echo rc=$?
opened 1000 ptmx master fds (expect <= 1000), last error=Operation not supported by device(19)
VULNERABLE: /dev/pts/1000 exists -> unit 1000 was allocated, ptis[1000] out-of-bounds read+write taken
rc=2

# run as nobody (UNPRIVILEGED — identical):
$ su -m nobody -c /tmp/ptmx_limit_offbyone; echo rc=$?
opened 1000 ptmx master fds (expect <= 1000), last error=Operation not supported by device(19)
VULNERABLE: /dev/pts/1000 exists -> unit 1000 was allocated, ptis[1000] out-of-bounds read+write taken
rc=2